The present invention generally relates to an abnormality detecting system for a copying machine and, more particularly, to an abnormality detecting device for detecting a failure occurring in the scanning movement of the copying machine.
In a copying machine of a scanning type, the distance over which the scanning movement is effected is controlled in dependence on the length of the original or the copying paper in order to increase the copying efficiency. This control of the scanning movement is available in two systems, i.e., a so-called step-return system and a so-called random return system. In the step-return system, a plurality of predetermined return positions are provided so that one of them can be selected according to the size of the original and/or the copying paper. On the other hand, in the random return system, the return position can be variable according to the length of the original and/or the copying paper.
With a diversity of control systems recently available for copying machines, trouble shooting associated with the copying operation must be carried out in every detail and this is true of the abnormality detection of a scan moving means. However, in the above described random return system, since the return position varies at random, and since it is therefore impossible to predetermine a timer for defining the timing at which any abnormality should be detected, the detection of the abnormality which would occur during the return movement cannot be achieved accurately.